The invention relates generally to the cutting or grooving of rubber or other heat sensitive materials. The invention more particularly relates to the grooving of rubber tires used on various vehicles, including trucks and other motor vehicles and to a cutting head member for a resistance-heated tire groover. The invention also relates to a resistance-heated tire groover that incorporates the disclosed cutting head member and facilitates the grooving of rubber tires in a rapid, efficient, and precise manner.
It has long been known that tires for various vehicles, although worn smooth as a result of extended operation on abrasive road surfaces, nonetheless retain significant amounts of rubber on their circumferential surfaces so that new tread patterns may be cut or "grooved" into such surfaces, thereby allowing the tires to be returned to service and their operable lives extended for thousands of additional miles. Such new tread patterns are typically formed by cutting a new or deepened groove at the precise tread location of an existing groove which has grown shallow as the tire has worn. By "superimposing" a new or deepened groove at the precise location of a worn groove, the original tire tread pattern can be recreated. It is believed that the performance of a regrooved tire is adversely affected when the original tread pattern is not accurately recreated.
Previous tire groovers have operated by means of a heated cutting blade that slices through the rubber material on the circumferential surface of the tire being grooved. Such a tire groover is discussed and referenced in U.S. Pat. No. 4,797,999, to Van Alstine, which is hereby incorporated in its entirety herein by reference. The tire groover shown in the U.S. Pat. No. 4,797,999, patent employed a plurality of slidable metal clamping spacers for securing the ends of the U-shaped blade to the cutting head housing. The ends of the U-shaped blade where interposed between metal spacers, and a floating insulator was slidably interposed between the metal spacers at a location between the ends of the blade. A single tightening means abutting one of the metal clamping spacers was provided. The single tightening means acted to secure (and squeeze) both ends of the blade, the metal clamping spacers, and the floating insulator against each other and the housing.
The dimensions of U-shaped cutting blades for use in conjunction with known tire groovers vary significantly. For example, different thicknesses of metal can be used to formulate such blades. In addition, different blade widths are often employed depending upon the width of the desired groove. As a result of these variations in blade dimension, it was found that the cutting blade, once secured by the tightening means, was often not in a centered position with respect to the housing of tool. Since an operator typically uses the tool's housing as an indicator for guiding the tool along an existing worn groove, it was found that such an off-center orientation often resulted in the creation of a new groove which did not coincide in position with the worn groove. The off-center orientation of the blade thus made it difficult for an operator to accurately recreate the original tread pattern.
FIG. 1 is an exemplary diagram showing a cross-sectional view of a known cutting member 10 holding a substantially U-shaped blade 20. Cutting head member 10 has first and second subhousings 10a, 10b, respectively. First and second subhousings 10a, 10b are separated by a distance H. A plurality of metal clamping spacers 30 are slidably interposed between subhousings 10a, 10b. A floating insulator 40, for electrically insulating metal clamping spacers 30 on either side of floating insulator 40, is slidably interposed within metal clamping spacers 30. Blade 20 has a width W and is formed in part from first and second ends 20a, 20b which are interposed between metal clamping spacers 30. A screw 50 is threadably engaged to second subhousing 10b so that when screw 50 is tightened, first and seconds end 20a, 20b, metal clamping spacers 30 and floating insulator 40 tighten against each other and against subhousing 10a.
As shown in FIG. 1, as screw 50 is tightened, first and second ends 20a, 20b are symmetrically compressed so that they are no longer separated by a distance W. In addition, the metal clamping spacers 30, fixed insulator 40 and blade 20 all shift to the left a distance T as screw 50 is tightened. Once screw 50 is tightened, it can be seen that blade 20 is no longer centered with respect to subhousings 10a, 10b. More particularly, once screw 50 is tightened, blade 20 is "off-center" a distance d.
It is an object of this invention to eliminate the of-center orientation of the cutting blade in known tire groovers.
It is a further object of this invention to enable an operator to profile a cutting blade within a cutting head in a non-symmetrical shape.